Printhead that evacuates air from a supply manifold
Printheads for jetting a print fluid. In one embodiment, a printhead comprises a main body configured to attach to a stack of plates, where the stack of plates forms a row of jetting channels configured to jet droplets of a print fluid. The main body includes a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, a cavity, and a semi-permeable membrane disposed between the cavity and the supply manifold.
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The following disclosure relates to the field of image formation, and in particular, to printheads and the use of printheads.
BACKGROUNDImage formation is a procedure whereby a digital image is recreated on a medium by propelling droplets of ink or another type of print fluid onto a medium, such as paper, plastic, a substrate for 3D printing, etc. Image formation is commonly employed in apparatuses, such as printers (e.g., inkjet printer), facsimile machines, copying machines, plotting machines, multifunction peripherals, etc. The core of a typical jetting apparatus or image forming apparatus is one or more liquid-droplet ejection heads (referred to generally herein as “printheads”) having nozzles that discharge liquid droplets, a mechanism for moving the printhead and/or the medium in relation to one another, and a controller that controls how liquid is discharged from the individual nozzles of the printhead onto the medium in the form of pixels.
A typical printhead includes a plurality of nozzles aligned in one or more rows along a discharge surface of the printhead. Each nozzle is part of a “jetting channel”, which includes the nozzle, a pressure chamber, and an actuator, such as a piezoelectric actuator. A printhead also includes a drive circuit that controls when each individual jetting channel fires based on image data. To jet from a jetting channel, the drive circuit provides a jetting pulse to the actuator, which causes the actuator to deform a wall of the pressure chamber. The deformation of the pressure chamber creates pressure waves within the pressure chamber that eject a droplet of print fluid (e.g., ink) out of the nozzle.
Drop on Demand (DoD) printing is moving towards higher productivity and quality, which requires small droplet sizes ejected at high jetting frequencies. The print quality delivered by a printhead depends on ejection or jetting characteristics, such as droplet velocity, droplet mass (or volume/diameter), jetting direction, etc. Unfortunately, air bubbles may be induced into the print fluid, which can negatively affect the jetting characteristics.
SUMMARYEmbodiments described herein provide an enhanced printhead that is able to remove air/gas from a supply manifold in the printhead. A supply manifold in a printhead provides a fluid path for a print fluid between a fluid source and a row of jetting channels of the printhead. To remove air/gas from the print fluid, the printhead has a cavity proximate to the supply manifold, and a semi-permeable membrane disposed between the cavity and the supply manifold. As the print fluid flows through the supply manifold, air in the print fluid is able to escape through the semi-permeable membrane and into the cavity, while the print fluid is contained in the supply manifold by the semi-permeable membrane. A vacuum may be applied to the cavity to assist in drawing the air from the print fluid and through the semi-permeable membrane. Evacuation of the air from the print fluid advantageously allows for more consistent droplet formation by the jetting channels and higher print quality.
One embodiment comprises a printhead that includes a main body configured to attach to a stack of plates, where the stack of plates forms a row of jetting channels configured to jet droplets of a print fluid. The main body includes a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, a cavity, and a semi-permeable membrane disposed between the cavity and the supply manifold.
Another embodiment comprises a printhead that includes a main body, and a stack of plates attached to the main body, and that form a row of jetting channels configured to jet droplets of a print fluid. The main body includes a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, a cavity fluidly isolated from the supply manifold, and a semi-permeable membrane disposed between the cavity and the supply manifold that is permeable to air and impermeable to the print fluid.
Another embodiment comprises a printhead that includes a rigid main body that includes a supply manifold for a print fluid, and a stack of plates attached to an interface surface of the main body, and that form a row of jetting channels configured to jet droplets of the print fluid. The main body includes a first supply port and a second supply port on an inlet surface opposite the interface surface, where the first supply port and the second supply port are separated by a distance along a length of the main body. The main body includes the supply manifold comprising a manifold duct that extends along the interface surface of the main body, a first fluid passage fluidly coupled between the first supply port and a first end of the manifold duct, and a second fluid passage fluidly coupled between the second supply port and a second end of the manifold duct. The main body includes a cavity, and a semi-permeable membrane disposed between the manifold duct and the cavity along a length of the manifold duct.
The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate any scope particular embodiments of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later.
Some embodiments of the present disclosure are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings.
The figures and the following description illustrate specific exemplary embodiments. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments and are included within the scope of the embodiments. Furthermore, any examples described herein are intended to aid in understanding the principles of the embodiments, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the inventive concept(s) is not limited to the specific embodiments or examples described below, but by the claims and their equivalents.
Jetting channel 202 as shown in
In
Main body 302 also includes one or more supply ports 330 on inlet surface 313 that are configured to receive a print fluid from a fluid supply. For example, supply ports 330 may be connected to a fluid reservoir via hoses to receive print fluid from the fluid reservoir. Supply ports 330 are separated by a distance along a length of main body 302, such as on opposing sides of access hole 310. Supply manifold 314 is configured to provide a fluid path for the print fluid from supply ports 330 to the row of jetting channels 202, and the structure of supply manifold 314 is described in more below. Although not visible in
In
Printhead 100 is enhanced in this embodiment with an air removal structure that assists in removing air from print fluid that flows within manifold duct 316. For the air removal structure, main body 302 includes a cavity 520, which comprises an empty space within main body 302 that is fluidly isolated from supply manifold 314. Cavity 520 is shown above manifold duct 316 in
In one embodiment, main body 302 may also include an air vent 524 coupled to cavity 520. Air vent 524 is configured to expel air that accumulates within cavity 520. Main body 302 may also include a vacuum port 526 coupled to air vent 524. Vacuum port 526 is configured to connect to a vacuum source (not shown) to draw or create a negative pressure or vacuum within cavity 520.
The air removal structure in printhead 100 assists in removing air or gas bubbles that form in a print fluid. Air trapped in the print fluid can affect the jetting characteristics of the jetting channels 202 resulting in lower print quality. By removing air from the print fluid that flows in supply manifold 314, the print fluid supplied to the jetting channels 202 will be free or substantially free of air or gas bubbles. One technical benefit is that jetting of the print fluid by the jetting channels 202 will be more reliable and consistent, which results in higher print quality. Another benefit of the air removal structure is that it can act to dampen pressure waves generated by jetting operations. Semi-permeable membrane 522 may have some flexibility (e.g., when comprising a thin plate or membrane) and fluid menisci may form in the pores or openings in semi-permeable membrane 522. Both of these characteristics act to dampen pressure waves generated by jetting operations.
Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. The scope of the invention is defined by the following claims and any equivalents thereof.
Claims
1. A printhead comprising:
- a main body comprising an elongated member made from a rigid material; and
- a stack of plates affixed to an interface surface of the main body, wherein the stack of plates forms a row of jetting channels configured to jet droplets of a print fluid;
- wherein the main body includes: an inlet surface that is opposite the interface surface; a first supply port and a second supply port on the inlet surface configured to connect to a fluid reservoir via hoses to receive the print fluid from the fluid reservoir, wherein the first supply port and the second supply port are separated by a distance along a length of the main body; a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, wherein the supply manifold is formed by: a manifold duct cut along a length of the interface surface of the main body from a first end to a second end, wherein a length of the manifold duct is at least as long as the row of jetting channels; a first fluid passage that fluidly couples the first supply port to the first end of the manifold duct; and a second fluid passage that fluidly couples the second supply port to the second end of the manifold duct; a cavity that runs the length of the manifold duct; and a semi-permeable membrane disposed between the cavity and the manifold duct along the length of the manifold duct.
2. The printhead of claim 1 wherein:
- the main body further includes an air vent coupled to the cavity.
3. The printhead of claim 2 wherein:
- the main body further includes a vacuum port attached to the air vent, and configured to couple to a vacuum source to create a vacuum in the cavity.
4. The printhead of claim 1 wherein:
- the semi-permeable membrane comprises a plate of metallic material having a plurality of holes in the range of 10-20 microns.
5. A printhead comprising:
- a main body comprising an elongated member made from a rigid material; and
- a stack of plates affixed to an interface surface of the main body, and that form a row of jetting channels configured to jet droplets of a print fluid;
- wherein the main body includes: an inlet surface that is opposite the interface surface; a first supply port and a second supply port on the inlet surface configured to connect to a fluid reservoir via hoses to receive the print fluid from the fluid reservoir, wherein the first supply port and the second supply port are separated by a distance along a length of the main body; a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, wherein the supply manifold includes an elongated groove on the interface surface configured to receive the print fluid at opposing ends via the first supply port and the second supply port, and to convey the print fluid towards a center; a cavity fluidly isolated from the supply manifold; and a semi-permeable membrane disposed between the cavity and the supply manifold that is permeable to air and impermeable to the print fluid, and is configured to allow air in the print fluid to escape into the cavity as the print fluid flows through supply manifold.
6. The printhead of claim 5 wherein:
- the cavity is configured to accumulate air that escapes through the semi-permeable membrane from the print fluid flowing in the supply manifold; and
- the main body further includes an air vent coupled to the cavity that is configured to expel the air that accumulates in the cavity.
7. The printhead of claim 6 wherein:
- the main body further includes a vacuum port attached to the air vent, and configured to couple to a vacuum source to create a vacuum in the cavity; and
- the vacuum in the cavity is configured to assist in drawing the air out of the print fluid flowing in the supply manifold and through the semi-permeable membrane.
8. The printhead of claim 5 wherein:
- the semi-permeable membrane comprises a plate of metallic material having a plurality of holes in the range of 10-20 microns.
9. A printhead comprising:
- a rigid main body that includes a supply manifold for a print fluid; and
- a stack of plates attached to an interface surface of the main body, and that form a row of jetting channels configured to jet droplets of the print fluid;
- wherein the main body includes: a first supply port and a second supply port on an inlet surface opposite the interface surface, wherein the first supply port and the second supply port are separated by a distance along a length of the main body; the supply manifold comprising: a manifold duct that extends along the interface surface of the main body; a first fluid passage fluidly coupled between the first supply port and a first end of the manifold duct; and a second fluid passage fluidly coupled between the second supply port and a second end of the manifold duct; a cavity; and a semi-permeable membrane disposed between the manifold duct and the cavity along a length of the manifold duct.
10. The printhead of claim 9 wherein:
- the main body further includes an air vent coupled to the cavity.
11. The printhead of claim 10 wherein:
- the main body further includes a vacuum port attached to the air vent, and configured to couple to a vacuum source to create a vacuum in the cavity.
12. The printhead of claim 9 wherein:
- the length of the manifold duct is at least as long as the row of jetting channels.
20040004649 | January 8, 2004 | Bibl |
20060103699 | May 18, 2006 | Hoisington |
20170341410 | November 30, 2017 | Otis |
Type: Grant
Filed: Mar 6, 2018
Date of Patent: Aug 27, 2019
Assignee: Ricoh Company, Ltd. (Tokyo)
Inventor: Hiroshi Nishimura (West Hills, CA)
Primary Examiner: Geoffrey S Mruk
Application Number: 15/913,787
International Classification: B41J 2/19 (20060101); B41J 2/14 (20060101); B41J 2/175 (20060101);